Coach K has adjusted his recruiting philosophy over the years.
Through the early 2000s, he recruited as much talent as possible. This meant he sometimes had to swim with the sharks and make deals with crack peddling AAU coaches (Corey Maggette) or set up an arrangement to allow a player's parent to work for a local booster (Chris Duhon).
However, losing Shaun Livingston to the NBA draft before he ever played a minute in Cameron drove Coach K over the edge, so he started recruiting more reliable four-year players. There were a few exceptions like Kyrie Irving and Josh McRoberts, but for the most part, he tried getting guys who would stay for three or four years.
During this era, he won a lot of games and eventually a national title in 2010, but he also suffered a number of blowout tournament losses once Duke reached the regional rounds to teams like Louisville, Villanova and Arizona in addition to a few huge, embarrassing early-round failures (Lehigh, VCU, West Virginia).
So Coach K changed into his bathing suit and started swimming with the sharks again. Of course this was not successful in 2014 because he suffered yet another huge, embarrassing failure against Mercer, but it worked out nicely for him in 2015.
But he's JB's buddy so it's all good!